This study will test the hypothesis that AA is due, in part, to activating the peripheral opioid system. This study will also compare the analgesic effects and impact on peripheral opioid release of needling points adjacent to vs. distal to the site of pain. This will provide needed information about the important of the proximity of acupuncture to the painful site in localized inflammatory conditions. Additionally, this study will examine the analgesic effects and impact on peripheral opioid release of low vs. high frequency electrical stimulation in order to better understand how to optimize AA. They will use a rat model of localized persistent inflammation to distinguish centrally released opioid petides from peripherally released ones during the EA treatment The local analgesic effect of EA will be assessed by the intraplantar administration of opioid antagonists. The specific aims of this proposed study are: 1) To determine the effect of EA on inflammatory hyperalgesia, paw withdrawal latency test and G-30; 2) To examine the effect of EA on peripheral opioid release; 3) To evaluate the effect of acupuncture points and electrical frequency of EA on peripheral opioids release. 2 Hz and 100 Hz on G-30 and SJ-6; and 4) To document the levels and types of opioid peptides in the local tissue and peripheral lymphocytes in rats with persistent inflammatory pain.